1. Field of the Invention
The present invention relates to a method for forming a bit-line contact plug, and more particularly, the present invention relates to a method for forming a bit-line contact plug by directly etching the bit-line contact material layer.
2. Description of the Prior Art
In the semiconductor process, the single transistor with the constructed gate, source and drain usually requires contact plugs to form the electrical connections between the elements. It is known in the conventional method that a borophosphosilicate glass (BPSG) layer is first formed on the transistor then the positions of the contact plugs are defined by a photoresist layer. A conductive material is filled in the contact holes after the BPSG layer is etched away, to complete the fabrication of the bit-line contact plugs.
However, with the trend of narrower line widths, the inevitable alignment error while defining the contact plug positions causes misaligned contact holes, the failure of elements, and damage in the insulation of the gate structure. Therefore, a novel method is needed to form bit-line contact plugs for patterns with narrower line widths.